As gigabit line rates become more prevalent in the enterprise market, the need for higher-speed aggregation uplinks is expected to grow over the next few years, which is particularly true in data communications systems in which Gigabit Ethernet is readily available on desktop computers and switches. Many integrated circuit (IC) vendors are developing new switches and media access controllers (MACs) with 10 Gigabit Ethernet ports, to provide the required higher density uplinks, thereby providing the required bandwidth and avoiding the need for multiple single gigabit ports.
The most cost-sensitive point in such a network system is inside the central office or data center, in which data transmission links are between equipment in the same room, i.e. in adjacent racks or often in the same rack. The most prevalent transmission links are inter-switch links (ISL), in which multiple switches are stacked with a single back haul to the server or another switch. Although optical solutions are usually still required to meet the distance requirements from switch room to switch room, building-to-building and central office-to-central office, there is a large opportunity for rack-to-rack or shelf-to-shelf ISL cost reduction by utilizing low cost copper cables in place of optical modules.
Currently, designers are tapping a parallel cable approach known as 10 GBASE-CX4 transceiver module, which delivers a 10-Gbit/s interconnect over a maximum span of 15 meters. CX4 is an extension of a four-channel 10-Gbit/s XAUI interface and is available in 70-pin MSA transceiver modules, e.g. Xenpak, XPAK and X2. The 10GBASE-CX4 solution employs an Infiniband-style Twin-AX cable, in which eight 100-ohm differential Twin-AX cables are bundled into a single outer shield, i.e. four channels in and four channels out. The center conductors are 24 AWG wire for compatibility with printed circuit board termination inside the connector housing.
FIG. 1 illustrates a conventional Infiniband® 4× electrical receptacle, generally indicated at 1, for mounting in a front end of a standard transceiver housing, including a connector shroud 2 and a pair of latching bars 3 (one of which is shown) extending from a rectangular body 4. An EMI shield 6 extends from around a front end of the body 4 to prevent the passage of EMI into or out of the housing of the transceiver. A compression gasket 7, in the form of spring fingers 8, extends from the front face of the EMI shield 6 for contacting a faceplate or bezel (not shown) provided on the host device. The connector shroud 2 and the latching bars 3 extend through an opening in the faceplate, while the compression gasket 7 contacts the area around the opening. Accordingly, the EMI shield 6 must be constructed substantially larger than the connector shroud 2 and the latching bars 3 to ensure sufficient contact between the compression gasket 7 and the faceplate required to provide a proper EMI seal. Moreover, the standard receptacle 1 includes a pair of pins 9, which extends from the bottom of the body 4 to provide strain relief when soldered to plated holes in the transceiver's printed circuit board (PCB). Unfortunately, this arrangement increases the overall height of the transceiver, as the PCB must extend beside the body 4.
An object of the present invention is to overcome the shortcomings of the prior art by providing an electrical receptacle for a transceiver with a front EMI shield, which enables the overall height of the transceiver module to be reduced.